Methane flux of leaves in a tropical rainforest and a temperate conifer forest

We measured methane (CH₄) fluxes of leaves growing in a tropical rainforest and a temperate conifer forest using the closed static chamber method. Leaf samples were chosen from the canopy and forest floor of a tropical rainforest at Pasoh Forest Reserve, Peninsular Malaysia and a temperate forest at Kiryu Experimental Watershed (KEW), central Japan. At Pasoh, we sampled four species from the canopy (<i>Xanthophyllum stipitatum, Dipterocarpus sublamellatus, Ptychopyxis caput-medusae, Neobalanocarpus heimii</i>) and four species from the forest floor (<i>Alphonsea maingayi, Rinorea anguifera, Macaranga lowii, Neobalanocarpus heimii</i>). The leaves of <i>Elaeis guineensis</i> were also sampled at an oil palm plantation near the forest reserve area. At KEW, we sampled the leaves of <i>Chamaecyparis obtusa</i>, from both the top (18 m) and middle (16 m) of the canopy as well as leaves of <i>Eurya japonica</i> at the forest floor. Incubation experiments revealed that CH₄ was emitted from leaves of the tested species sampled at two sites, although CH₄ fluxes showed variations on a daily basis. These results suggest that tree leaves both at Pasoh and KEW might function as a small CH₄ source, but their contribution to the CH₄ exchange of the total forest ecosystem is very small compared to the soil CH₄ flux.